<?php

/*
 * This file is part of SwiftMailer. (c) 2004-2009 Chris Corbyn For the full copyright and license information, please view the LICENSE file that was distributed with this source code.
 */

/**
 * Handles Base 64 Encoding in Swift Mailer.
 * 
 * @package Swift
 * @subpackage Encoder
 * @author Chris Corbyn
 */
class Swift_Encoder_Base64Encoder implements Swift_Encoder {
	/**
	 * Takes an unencoded string and produces a Base64 encoded string from it.
	 * Base64 encoded strings have a maximum line length of 76 characters.
	 * If the first line needs to be shorter, indicate the difference with
	 * $firstLineOffset.
	 * 
	 * @param string $string
	 *        	to encode
	 * @param int $firstLineOffset        	
	 * @param int $maxLineLength,
	 *        	optional, 0 indicates the default of 76 bytes
	 * @return string
	 */
	public function encodeString($string, $firstLineOffset = 0, $maxLineLength = 0) {
		if (0 >= $maxLineLength || 76 < $maxLineLength) {
			$maxLineLength = 76;
		}
		
		$encodedString = base64_encode ( $string );
		$firstLine = '';
		
		if (0 != $firstLineOffset) {
			$firstLine = substr ( $encodedString, 0, $maxLineLength - $firstLineOffset ) . "\r\n";
			$encodedString = substr ( $encodedString, $maxLineLength - $firstLineOffset );
		}
		
		return $firstLine . trim ( chunk_split ( $encodedString, $maxLineLength, "\r\n" ) );
	}
	
	/**
	 * Does nothing.
	 */
	public function charsetChanged($charset) {
	}
}
